Two monitors doesn't work great for me because I always feel like one is "primary" and one "secondary", where all the crap like Slack and email that distracts me goes, which just hurts productivity.

I switched to an ultrawide, and though it's about the same amount of screen space I tend to organize it differently, keeping mostly on-task stuff visible. It's real nice to have 3 tabs of related code and an iOS simulator running as well as a console without having to tab switch.